An organic light emitting diode (OLED) display is a technology that realizes display using reversible discoloration generated by an organic semiconductor material under the driving of current. The OLED display is considered as the most promising new-generation display technology due to its advantages such as being ultralight and ultrathin, having high brightness, large viewing angle, low voltage, low power consumption, quick response and high resolution, being aseismic and bendable, having low cost and simple process, using less raw material, having high luminous efficiency and wide temperature range, and the like.
In terms of different driving manners, OLED displays can be classified into passive matrix OLED (PMOLED) displays and active matrix OLED (AMOLED) displays. Each light emitting unit of an AMOLED display is independently controlled by a thin film transistor (TFT). Compared to the PMOLED display, the AMOLED display attracts more attention due to its advantages such as having high brightness, high resolution, high efficiency and low power consumption, being easy to improve integration and miniaturization, being easy to realize large-area display, and so on.
At present, an important indicator for evaluating the performance of a display is the number of pixels per inch (PPI). The higher the PPI value of the display is, the higher the density at which the display can display an image is. Certainly, the higher the density of display is, the higher the fidelity is, and the more detailed the image is. In existing OLED displays, as the number of pixels per unit area becomes larger and larger, the number of signal lines of the pixel driving circuit will be multiplied. Since the pixel driving circuit is usually arranged in a frame portion of the OLED display, the increase in the number of signal lines means that the wiring complexity as well as the area of the pixel driving circuit are increased, which will seriously hinder the frame narrowing and thinning of the display device.